Device, system and methods for measurement of pressures in the urinary tract

ABSTRACT

A catheter for measuring pressure in the urinary tract of a patient includes a catheter body having a proximal and distal end. A plurality of lumens is formed in the catheter body, and an adaptor is coupled to the proximal end of the catheter body. The adaptor includes a port for each lumen. A first pressure sensor, typically including a balloon, is fluidically coupled to a first lumen and is configured and positioned to measure pressure in a urethra of the patient. A second pressure sensor, also typically including a balloon, is fluidically coupled to a second lumen and is configured and positioned on the catheter body to measure pressure in a bladder of the patient. An expandable retention member, which may be coupled to a third lumen, is positioned on the catheter body between the first and second expandable pressure sensors so that the catheter body may be retained at a selected location in the urinary tract to properly position the fluid pressure sensors in the bladder and urethra, respectively.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.15/153,314, filed May 12, 2016, now U.S. Pat. No. 10,542,924, whichclaims the benefit of priority to U.S. Provisional Application No.62/160,201, filed May 12, 2015, the entire content of which isincorporated herein by reference for all purposes.

BACKGROUND OF THE INVENTION 1. Field of the Invention

Embodiments described herein relate to devices, systems and methods formeasurement of pressure in the urinary tract. More specifically,embodiments described herein relate to a device, such as a catheter,positionable within the urinary tract (UT) for measurement of pressurein one or more locations in the UT such as the bladder and urethra.Still more specifically embodiments described herein relate to acatheter positionable within the urinary tract for measurement ofpressures within the bladder and urethra to facilitate placement of aneuromodulation device within the urinary tract for treatment of anoveractive bladder.

Urinary incontinence can be a common and distressing problem, which mayhave a profound impact on quality of life but which is oftenunderreported. In many cases, urinary incontinence results from anunderlying treatable medical condition. Urinary incontinence arises inboth men and women, with varying degrees of severity, and from differentcauses. In men, the condition most frequently occurs as a result ofprostatectomies which result in mechanical damage to the urethralsphincter. In women, urinary incontinence typically develops afterpregnancy when musculoskeletal damage has occurred as a result ofinelastic stretching of the structures which support the genitourinarytract. Specifically, pregnancy can result in inelastic stretching of thepelvic floor, the external sphincter, and the tissue structures whichsupport the bladder and bladder neck region. In each of these cases,urinary leakage typically occurs when a patient's abdominal pressureincreases as a result of stress, e.g., coughing, sneezing, laughing,exercise, or the like.

Treatment of urinary incontinence can take a variety of forms thougheach has drawbacks. Most simply, the patient can wear absorptive devicesor clothing, which is often sufficient for minor leakage events.Alternatively or additionally, patients may undertake exercises intendedto strengthen the muscles in the pelvic region, or may attempt abehavior modification intended to reduce the incidence of urinaryleakage.

In cases where such non-interventional approaches are inadequate orunacceptable, the patient may undergo surgery to correct the problem. Awide variety of procedures have been developed to correct urinaryincontinence in women. Several of these procedures are specificallyintended to support the bladder neck region. For example, sutures,straps or other artificial structures are often looped around thebladder neck and affixed to the pelvis, the endo-pelvic fascia, theligaments which support the bladder, or the like. Other proceduresinvolve surgical injections of bulking agents, inflatable balloons, orother elements to mechanically support the bladder neck.

In another approach, a stimulatory lead electrode is positioned tomodulate neural signals going to the bladder so as to decrease thesymptoms from an over active bladder. However, current devices do notprovide the surgeon with sufficient real time measurement of bladderand/or urinary sphincter pressure to assess the effectiveness oftreatment.

Accordingly, there exists a need for improved devices and methods formeasurement of pressures in the urinary tract.

BRIEF SUMMARY OF THE INVENTION

Various embodiments of the invention described herein provide devices(e.g., a catheter) systems and methods for measuring pressures atvarious locations in the urinary tract (UT). Many embodiments providedevices, systems and methods for measuring pressures at variouslocations in the urinary tract including for example the bladder. Stillmore specifically, embodiments provide devices, systems and methods formeasuring pressures at various locations in the urinary tract so thatthe effectiveness of a urinary incontinence treatment can be evaluated.Particular embodiments provide a catheter positionable within theurinary tract for simultaneous and/or sequential pressure (or related)measurement in the bladder and urethra to facilitate placement of aneuromodulation stimulation electrode for treatment of urinaryincontinence from an overactive bladder and other related conditions.Further, embodiments provide a method for real time measurement ofpressures in the urinary tract including the bladder and urinarysphincter to assess the effectiveness of placement of stimulation leadelectrode to neuro-modulate nerve impulses causing an over activebladder. As such, embodiments of the invention are particularly usefulfor improving the efficacy of various neuromodulation and otherprocedures for treatment of urinary continence and related conditions byproviding real time quantitative and/or qualitative data for assessingplacement of the stimulating electrode to produce the desired effect onthe urinary tract.

One embodiment provides a catheter for measuring pressure in the urinarytract of a patient comprising a catheter body having a proximal anddistal end and a plurality of lumens including at least a first, secondand third lumen; an adaptor coupled to the proximal end of the catheterbody, the adaptor including a plurality for ports including at least afirst, second and third port for fluidic coupling to the plurality oflumens; a first pressure sensor fluidically coupled to the first lumen,the first pressure sensor configured and positioned on the catheter bodyto be positioned and measure pressure in a urethra of the patient; asecond pressure sensor fluidically coupled to the second lumen, thesecond pressure sensor configured and positioned on the catheter body tobe positioned and measure pressure in a bladder of the patient; and anexpandable retention member fluidically coupled to the third lumen andpositioned on the catheter body between the first and second expandablepressure sensors, the expandable retention member configured when in anexpanded state to retain the catheter body at selected location in theurinary tract in response to a physiological force exerted on at least aportion of the catheter.

The retention member will typically comprise an expandable member suchas an expandable balloon that is expanded through the third lumen and isconfigured to retain the catheter body at a selected location in theurinary tract (including retaining the first sensor in the urethra andthe second sensor in the bladder, when subjected to one or morephysiological forces including hydrostatic pressure from the bladder aswell force resulting contraction of the bladder and/or contraction ofthe urinary sphincter.

The pressure sensors may correspond to a variety of pressure sensorsknown in the art including various solid state and/or a “MEMS” basedsensors. “MEMS” refers to a class of micro-electro-mechanical systemswhich typically comprise micro-fabricated miniaturized mechanical andelectro-mechanical elements (i.e., devices and structures). Also inpreferred embodiments, the first or second pressure sensor comprises oris otherwise positioned on an expandable member such as expandableballoon which may be inflated by means of the first or second lumens. Insuch embodiments, the expandable balloon may coupled by means of thefirst or second lumen, to an external pressure sensor such as amanometer which is coupled to the catheter via means of one or more ofthe ports (e.g., the first or second ports). The expandable pressuresensors are advanced to their selected locations in a non-expanded stateand then deployed to their expanded state once the catheter body is at aselected locations in the urinary tract. The expandable members/sensorsalso facilitate retention of the sensors at their respective locationsin the urethra and bladder.

The catheter body may be fabricated from a variety of medical polymersknown in the art including, for example, one or more of PEBAX,Polyethylene, HDPE (high density polyethylene), PET (polyethyleneteraphalate), polyurethane and the like. In preferred embodiments, thecatheter lumens have sufficient stiffness or hoop strength such that achange in pressure in one lumen does not cause a significant pressurechange (e.g., <5% preferably <2%). Such stiffness or hoop strength canbe achieved by use of one or more of the catheter materials, areinforcing braid (either internal or external to the lumen), or aninternal re-enforcing member (e.g., an internal polyimide tube or otherstiff polymer material known in the catheter arts which can includevarious radiated polymers materials known in the art such as variousradiated polyethylenes both LDPE and HDPE).

Also, in various embodiments, the catheter can be configured forplacement in either the male or female urinary tract. Suchconfigurations may include one more of length, diameter stiffness,length and position of the respective sensors. According to oneembodiment for the male anatomy, the first sensor, (the urethra pressuresensor) has a length of about 2 cm. According to another embodiment, forthe female anatomy, the first sensor, (the urethra pressure sensor) hasa length of about 1.5 cm. As used herein, the term “about” means within+/−10% of a stated value for a parameter, measurement, dimension,characteristic, physical property and the like.

Embodiments of the invention are particularly useful for making pressuremeasurements at two more locations in the urinary tract such as thebladder and urethra so as to facilitate a procedure to treat anoveractive bladder. In particular, this includes providing the doctorfeedback (by means of the pressure measurements) during the procedure onthe effectiveness of the treatment. The pressure measurements may bemade substantially simultaneously or sequentially, so to have anindication of a response by one more of the bladder, and urethralsphincter to a particular form of treatment or treatment stimulus.Typically, such a procedure will comprise placement and/or electricalcoupling of an electrical lead on an nerve enervating the bladder (e.g.the hypogastric plexuses and nerves, and the pelvic splanchnic nervesand the inferior hypogastric plexus) so as to provide anneuro-modulating signal that modulates or otherwise attenuates a nervesignal causing an unwanted contraction of the bladder. In anotherembodiment, the treatment for the overactive bladder may comprise thedelivery of electrical stimulations to the patient's foot from one ormore transcutaneous electrodes placed on the patients foot (e.g., thesole top portion, etc).

In an exemplary embodiment of using the invention, an embodiment of apressure measurement catheter such as an embodiment described isadvanced into the urinary tract (trans-vaginally for a woman,trans-penaly for a man) so as to position the first sensor at a firstlocation in the urethra and the second sensor in the bladder.Advancement may be done under image guidance and proper placementdetermined by imaging and/or pressure measurements from the first andsecond sensor. Then once the catheter is placed at the desired locationin the urinary tract, the retention member is inflated via the thirdlumen (or another lumen) so as to anchor or retain the catheter in placein response to once or more physiological forces including hydrostaticpressure from the bladder and/or a contractile force from one or more ofthe bladder or urethral sphincter. For embodiment having inflatable orotherwise expandable pressure sensor, one or both the sensor may beexpanded before, after or about the same time as the retention member soas to retain the pressure sensors at their selected locations in theurethra or bladder. (They along with the retention member can bedeflated for withdrawal of the catheter). Then pressure from therespective sensors can be takin over the course of a surgical or otherprocedure to treat an over active bladder. In particular, pressures maybe measured (either simultaneously or sequentially) from both sensors inresponse to an external stimulus to assess the effectiveness of thetreatment. In particular embodiments, that external stimulus maycorrespond to a neuro modulating electrical signal from an electrodeelectrically coupled to a nerve innervating the bladder (and causingunwanted contraction of the bladder) and/or the injection of fluid intothe bladder from the pressure measurement catheter or another catheter.In either case, the pressure measurement signals allows the doctor todetermine if the treatment has been effective by determining if unwantedbladder contraction are continuing to occur and/or what hydrostaticpressure in the bladder causes contraction. Multiple measurements may betaken over the course of the procedure (including before, during andafter) to determine the effectiveness of treatment. For treatmentsinvolving the neuromodulation signal, the physician can use the pressuremeasurement to assess the effectiveness of one or both of the waveformof the neuro-modulation signal as well as the placement of the electrodeto deliver the signal.

In related embodiments, pressure measurements can be made usingembodiments of the pressure measurement catheter described herein toassess the effectiveness of treatment for overactive bladder comprisingthe delivery of pulsed electrical signals to the patients foot from aplurality of electrodes placed on the patient's foot (e.g., on theplantar or dorsal side adjacent metatarsal bones). Specifically,pressures in the bladder (and/or urethral sphincter) can be measured todetermine a micturition volume threshold in the bladder and theeffectiveness of the delivered pulsed electrical signals in increasingthat threshold. The pressure measurements can be used to assist in oneor more of electrode placement on the patient's foot and/or tune or finetuning of the electrical signal waveform (e.g., in terms of pulse width,frequency, and amplitude) to optimize increases in the patient'smicturition volume threshold. Micturition volume threshold (MVT) isdefined herein as the volume of fluid in the bladder which results in acontraction and subsequent voiding of the bladder and thus it providesan indication of the effectiveness of treatment in reducing anoveractive bladder. This is the case due to the fact that a reduction inan over active bladder should result in an increased micturition volumethreshold. In one approach, MVT can be determined using an embodiment ofthe pressure measurement catheter to fill the bladder with fluid (e.g.,through an irrigation lumen) and then monitor the delivered volume atwhich bladder contraction and subsequent voiding occurs. Typically, theelectrical waveform will comprise a pulsed signal having a frequencyranging from about 1 Hz to 500 Hz a voltage ranging from about 1 V to50V and pulse width from about 0.1 to 3 ms. Pressure measurements can bemade using embodiments of the invention to tune and/or fine tune one ormore of these signal parameters so as optimize the increase inmicturition volume in the bladder in response to the delivery of theelectrical signals. In use, such approaches enable better clinicaloutcomes for the patent.

Further details of these and other embodiments and aspects of theinvention are described more fully below, with reference to the attacheddrawing figures.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an embodiment of a urinary tract pressure sensingcatheter constructed in accordance with the principles of the presentinvention.

FIG. 2 is a cross-sectional view taken along line 2-2 in FIG. 1.

FIG. 3 is a detailed view of a proximal adaptor of the urinary tractpressure sensing catheter of FIG. 1, showing the connection toindividual inflation source and pressure measurement sensors.

FIGS. 4A and 4B show use of the urinary tract pressure sensing catheterin measuring urinary tract pressure in a bladder and a urethra of apatient.

DETAILED DESCRIPTION OF THE INVENTION

Various embodiments described herein provide devices, apparatus andmethods for measuring pressures at various locations in the urinarytract (UT). Many embodiments provide a devices, systems and methods formeasuring pressures at various locations in the urinary tract includingfor example the bladder. Still more specifically embodiments providedevices, systems and methods for measuring pressures at variouslocations in the urinary tract so that the effectiveness of a urinaryincontinence treatment can be evaluated. Particular embodiments providea catheter positionable within the urinary tract for measurement ofpressures within the bladder and urethra to facilitate placement of aneuromodulation stimulation electrode within the urinary tract fortreatment of an over active bladder.

Referring now to FIG. 1, an embodiment of a catheter 10 for measuringpressure in the urinary tract includes a multi-lumen catheter body 20having at least a first lumen 21, a second, lumen 22, and a third lumen23 (FIG. 2), a proximal adapter 30 having one or more ports including atleast a first port 41, a second port 42, and a third port 43; a first orurethral sphincter pressure sensor 50, a second or bladder pressuresensor 60, and an anchoring or retention member 70. Typically adaptor 30will include at least three ports for coupling of one or more fluidlines (e.g. for irrigation and drainage), pumps, syringes, sensors,manometers, electrical cabling and the like, but ports are contemplatedincluding a fifth and six port for other purposes. In particular, afourth port may connect to a fourth lumen (not shown) which runs all theway to a distal tip of the catheter body 20 to permit fluid infusionand/or aspiration from the bladder.

The urethral sphincter pressure sensor 50 and the bladder pressuresensor 60 will typically include inflatable bladders where an inflationpressure can be monitored as a measure of physiologic pressure at thepoint of inflation. Pressure measurement transducers may be providednear the inflation source and/or within the inflatable bladders. Otherlocations are also considered. As the inflation region will be closed,the pressure at all points within the pressurized region will bevirtually identical so long as the inflation medium is not flowing.

FIG. 3 shows an exemplary arrangement for inflating the inflatablebladders for both sensors 50 and 60 as well as the anchoring orretention member 70. In this arrangement, pumps 81, 82, and 83 areconnected to ports 41, 42, and 43, respectively. The first pump 81,which may be a syringe, an insufflator, or any other common medicalballoon inflation device known in the art, is used to inflate theanchoring or retention member 70 and may or may not include a pressuresensor (none is shown in FIG. 3). The second pump 82 is connected toinflate the inflatable bladder of the urethral sphincter pressure sensor50 and includes a pressure transducer 84 which provides the pressurewithin the urethra U at the bladder sphincter. The third pump 83 isconnected to inflate the inflatable bladder of the bladder pressuresensor 60 and includes a pressure transducer 85 which provides thepressure within the bladder. The pressure transducers may be simplemechanical gauges or may be solid state transducers that provide anelectronic output. Manometers and other know medical pressuremeasurement devices could also find use.

As shown in FIG. 4A, the catheter 10 is initially introducedtrans-urethrally to position the uninflated sensors 50 and 60 andanchoring or retention member 70. The urethral sphincter sensor 50 ispositioned to be inflated within and receive pressure readings from thesphincter muscle US when the anchoring or retention member 70 isinflated and drawn back against the bladder neck OS, as is typicallydone with a Foley catheter. The urethral sphincter sensor 50 has severalembodiments. In one embodiment, it is split into two sections, one forthe internal urethral sphincter and one for the external urethralsphincter. In the male version of the catheter the sensor is locatedapproximately 2.5 cm distal to the bladder neck, and extendsapproximately 2.0 cm of urethral length. In the female version of thecatheter the sensor is located approximately 1.8 cm distal to thebladder neck, and extends approximately 1.5 cm of urethral length. Thebladder pressure sensor 60 extends a short distance distally of theanchoring or retention member 70 and is configured to remain in thecenter portion of the bladder B. The sensors and balloon are configuredto be expandable and retractable such that during insertion or removalof the catheter they do not provide significant resistance (i.e., thecatheter push or pull force is less than a selected value, e.g., lessthan 1.0 pound, more preferably less than 0.5 lbs, still more preferablyless than 0.25 lbs).

According to one or more embodiments, the catheter body 20 may besufficiently rigid (e.g., radial rigidity or stiffness) and/or may havesufficient hoop strength to prevent pressure changes in an individuallumen from significantly impacting the pressure in another lumen, e.g.any impact will result in a deviation below about 5%, preferably belowabout 2%. In other words, the lumens are configured to preventhydrostatic pressure cross-talk from one lumen to the next. Preferably,though, the catheter as a whole will remain sufficiently compliant to beadvanced and manipulated in and through the intended patient anatomy forthe clinical use scenarios. In specific embodiments, the catheter lumenshave sufficient stiffness or hoop stress such that any change inpressure in one lumen resulting from a change in an adjacent lumen willremain at or below, preferably below, about 5%, preferably 2%. Suchstiffness or hoop strength can be achieved by any one or more of thefollowing: (1) choice of catheter materials, (2) catheter/lumendimensions, (3) use of a reinforcing braid (internal external to thelumen), and/or (4) an internal re-enforcing lumen. In variousembodiments the radial rigidity (also described herein as radialstiffness), of any one of lumens 21, 22 and 23 (or other lumen ofcatheter 10) can be in the range of about 1 to about 100 N/mm, morepreferably in a range of about 20 to about 100 N/mm and still morepreferably in a range of about 50 to about 100 N/mm with specificembodiments of 5, 10, 20, 25, 30, 40, 45, 50, 55, 60, 70, 75, 80, 90 and95 N/mm; whereas the hoop strength can be in a range of about 0.25 to 5lbs, more preferably about 0.5 to 5 lbs, and still more preferably about1 to 10 lbs, with specific embodiments of 0, 5, 1, 2, 2, 5, 3, 4, 5, 6,7, 8 and 9 lbs of force.

In an exemplary embodiment of a method of using the invention, anembodiment of a pressure measurement catheter 10 is advanced into theurinary tract (trans-vaginally for a woman, trans-penaly for a man) soas to position the first sensor 50 at a first location in the urethra Uand the second sensor 60 in the bladder. Advancement may be done underimage guidance, and proper placement may be determined by imaging and/orby pressure measurements using the first and/or second sensors 50 or 60.Once the catheter 10 is placed at the desired location in the urinarytract, the retention member 70 is inflated via the third lumen 23 (oranother lumen) so as to anchor or retain the catheter 10 in place toinhibit movement in response to physiological forces such as hydrostaticpressure from the bladder B and/or a contractile force from one or moreof the bladder or urethral sphincter. For embodiments having aninflatable or otherwise expandable pressure sensor, as illustrated, oneor both the sensors 50 and 60 may be expanded before, after or about thesame time as the retention member 70 to hold the pressure sensors attheir selected locations in the urethra U or bladder. The sensors andthe retention member can be deflated prior to withdrawal of thecatheter.

Pressure from the sensors 50 and 60 can be taken continuously orperiodically over the course of a surgical or other procedure to treatan overactive bladder or for any other purpose. In particular, pressuresmay be measured (either simultaneously or sequentially) from bothsensors 50 and 60 in response to an external stimulus to assess theeffectiveness of a treatment for an overactive bladder. In particularembodiments, external stimulus may effected by applying a neuromodulating electrical signal from an electrode electrically coupled to anerve innervating the bladder to induce contraction of the bladder,Alternatively or additionally, fluid may be injected into the bladder,typically using a lumen in the pressure measurement catheter 10 oranother catheter. In either case, pressure measurements allow the doctoror other medical practitioner to determine if the treatment has beeneffective by determining if unwanted bladder contraction is continuingto occur and/or what hydrostatic pressure in the bladder causes suchcontraction. Multiple measurements may be taken over the course of theprocedure (including before, during and after) to determine theeffectiveness of treatment. For treatments involving use of theneuromodulation signal, the physician can use the pressure measurementto assess the effectiveness of one or both of the waveform of theneuro-modulation signal as well as the placement of the electrode todeliver the signal.

In related embodiments, pressure measurements can be made usingembodiments of the pressure measurement catheter 10 described herein toassess the effectiveness of treatment for overactive bladder comprisingthe delivery of pulsed electrical signals to the patients foot from aplurality of electrodes placed on the patient's foot (e.g., on theplantar or dorsal side adjacent metatarsal bones). Specifically,pressures in the bladder (and/or urethral sphincter) can be measured todetermine a micturition volume threshold in the bladder and theeffectiveness of the delivered pulsed electrical signals in increasingthat threshold. The pressure measurements can be used to assist in oneor more of electrode placement on the patient's foot and/or tuning orfine tuning of the electrical signal waveform (e.g., in terms of pulsewidth, frequency, and amplitude) to optimize increases in the patientsmicturition volume threshold. As described above, micturition volumethreshold (MVT) is the volume of fluid in the bladder which results in acontraction and subsequent voiding of the bladder. As such, an increasein the MVT is one indication of the effectiveness of treatment inreducing an overactive bladder. For example, MVT can be determined usingan embodiment of the pressure measurement catheter 10 to fill thebladder with fluid (e.g., through an irrigation lumen) and thenmonitoring the delivered volume at which bladder contraction and voidingoccurs. Typically, the stimulating electrical waveform comprises apulsed signal having a frequency ranging from about 1 Hz to 500 Hz avoltage ranging from about 1 V to 50 V and pulse width from about 0.1 to3 ms. Pressure measurements can be made using embodiments of theinvention to tune and/or fine tune one or more of these signalparameters so as optimize the increase in micturition volume in thebladder in response to the delivery of the electrical signals.

The foregoing description of various embodiments of the invention hasbeen presented for purposes of illustration and description. It is notintended to limit the invention to the precise forms disclosed. Manymodifications, variations and refinements will be apparent topractitioners skilled in the art. For example, the embodiments of thepressure measurement catheter can be modified in one or more of size,shape or other property for various pediatric and even neonatalapplications.

Elements, characteristics, or acts from one embodiment can be readilyrecombined or substituted with one or more elements, characteristics oracts from other embodiments to form numerous additional embodimentswithin the scope of the invention. Moreover, elements that are shown ordescribed as being combined with other elements, can, in variousembodiments, exist as standalone elements. Hence, the scope of thepresent invention is not limited to the specifics of the describedembodiments, but is instead limited solely by the appended claims.

What is claimed is:
 1. A method for measuring pressure at multiple locations in the urinary tract of a patient to facilitate a treatment for urinary incontinence, the method comprising: advancing a catheter having a first and second pressure sensor into the urinary tract of a patient so as position the first pressure sensor at a first location in a urethra of the patient and the second pressure sensor at a second location in a bladder of the patient, the catheter including a plurality of lumens including at least a first lumen and a second lumen, the first pressure sensor fluidically coupled to the first lumen and the second pressure sensor fluidically coupled to the second lumen, wherein the plurality of lumens are configured so as to minimize an effect of a pressure change in one lumen of the plurality of lumens on a pressure in another lumen of the plurality of lumens; expanding an expandable retention member so as to retain the first pressure sensor at the first location and the second pressure sensor at the second location during exertion of a physiological force on the catheter; and measuring pressures at the first location and the second location in response to an external stimulus.
 2. The method of claim 1, wherein the pressures at the first and second location are measured substantially simultaneously.
 3. The method of claim 1, wherein the pressures at the first and second location are measured sequentially.
 4. The method of claim 1, wherein the external stimulus comprises an electrical signal.
 5. The method of claim 4, wherein the electrical signal comprise a neuromodulation signal generated by an electrode electrically coupled to a nerve innervating the bladder.
 6. The method of claim 1, wherein the external stimulus comprises adding fluid to the bladder from outside the body.
 7. The method of claim 1, wherein the physiological force corresponds to a hydrostatic pressure from fluid in the patient's bladder.
 8. The method of claim 1, wherein the physiological force corresponds to a force resulting from a contraction of at least one of the patient's bladder or urethral sphincter.
 9. The method of claim 1, wherein the at least one of the first or second pressure sensors comprises an expandable member, the method further comprising expanding at least of the first or second pressure sensors.
 10. The method of claim 1, wherein the catheter is configured such that measurement of the pressure at either of the locations is not substantially affected by a position of a pressure sensor at the other location.
 11. The method of claim 10, wherein the catheter includes a plurality of lumens including at least a first a second lumen, the first pressure sensor fluidically coupled to the first lumen and the second pressure sensor fluidically coupled to the second lumen.
 12. The method of claim 11, wherein the plurality of lumens are so as to minimize an effect of a pressure change in one lumen of the plurality of lumens on a pressure in another lumen of the plurality.
 13. The method of claim 1, wherein each lumen of the plurality of lumens has sufficient stiffness or hoop strength such that a pressure change in one lumen of the plurality causes a 5% or less pressure change in another lumen of the plurality of lumens.
 14. The method of claim 1, wherein each lumen of the plurality of lumens has sufficient stiffness or hoop strength such that a pressure change in one lumen of the plurality causes a 2% or less pressure change in another lumen of the plurality.
 15. The method of claim 1, wherein a radial rigidity of each lumen of the plurality of lumens is in a range of about 20 to 100 N/mm.
 16. The method of claim 1, wherein the radial rigidity of each lumen of the plurality of lumens is in a range of about 50 to 100 N/mm. 